The present invention relates to a mass compensated impacting, i.e. tamping and/or striking, system of the type including at least one pair of tools constituting two impacting, i.e. tamping or striking, tools, respectively, which are connected to a common tool carrier and vibrate in phase opposition to one another.
In machines equipped with vibrating tools, for example ground compacting machines for road construction, excavating work in mines etc., there generally exists the difficulty that the vibrating masses transfer vibrations to the machine frame. These vibrations subject the machine frame to stresses which in the course of time may lead to material fatigue and damage. Various efforts have therefore been made to produce mass compensated tamping and/or striking machines.
In most of the prior art vibratory machines the vibrating masses are coupled together in a resilient manner and the system made up of the two vibrating masses is in turn coupled to the machine frame in a resilient manner. Such approaches to compensation are principally encumbered by the drawback that the coupling of the resilient mass systems gives rise to a number of inherent resonant frequencies. If the vibratory frequency of the tools should coincide with, or reach the vicinity of, such a frequency, the resonant behavior of the system may generate uncontrollable vibratory motion and forces so that operation in these frequency ranges must be avoided. In daily practice it is necessary, however, to adapt the vibrating frequency of the tools to the conditions encountered, e.g. to the consistency of the ground if compacting tools are being used, or to the material consistency if the machine is to perform excavation work. Therefore, there will be occasions when the optimum frequency for a particular task falls into one of the ranges which must be avoided.
If a plurality of tools are to be used in a common tool carrier or machine frame, respectively, it is practically impossible to achieve mass compensation if the vibrating masses are resiliently coupled together. The tool carrier may then be subjected to uncontrollably high stresses.